1. Technical Field
The present invention relates generally to gas burner pilot assemblies and control systems for gas burners ignited by a pilot flame, and more specifically to relighter system for a gas burner pilot assembly used with fuel pipeline heaters.
2. Background Prior Art
A specialized type of heater apparatus is necessary for use on fuel pipelines, including natural gas pipelines. With natural gas fuel pipelines, the need for such heaters arises to prohibit the condensation of hydrocarbons in the pipelines. When there is a reduction in the pressure of the natural gas within the pipeline, such as is typically the case when a percentage of the gas in a main line is diverted to a separate pipeline to service a municipality or the like, the sudden loss in internal pipeline pressure may result in the development of undesirable condensation of hydrocarbons in the pipeline. The development of hydrocarbon condensation may lead to an obstruction or faulty flow of gas. This possible hydrocarbon condensation problem may be avoided by heating the pipeline.
Many gas burning heaters in use today often include a manually operated pilot flame ignition. These manually operated pilot flame ignitions are often provided without safety features such as reliable relighting of an extinguished pilot or main burner shut-off features. Further, many of the gas heaters presently being used are not reliable for preventing hydrocarbon condensation in the pipeline because they do not have safety features for detecting and reacting to pilot-burner flame failure. Further, because many of the heaters presently in use do not have reliable relighting features, they often require continual pilot flames even though the actual burner is used infrequently. The use of continual pilot flames, however, results in wasted fuel and unnecessary pilot burn time, thereby increasing the cost and decreasing the overall life of the burner components.
Additionally, other relighting systems presently in use in the industry have a pilot assembly with a structure having an ignitor terminal extending into the pilot flame. This often results in the deterioration of the ignitor terminal due to constant exposure in the pilot flame and/or loss of the important tolerance of the spacing of the ignitor terminal.
Many of these noted disadvantages have been overcome by U.S. Pat. No. 6,089,856, entitled xe2x80x9cPilot Control Assembly,xe2x80x9d and U.S. Pat. No. 5,927,963, a divisional of the ""856 patent. Both of these U.S. patents are commonly owned by the assignee of the present invention, and are hereby incorporated by reference herein. The inventions of the ""856 and ""963 patents resolved many of the above noted disadvantages, primarily by providing a specific structure of a pilot assembly, and by providing a pilot control means which optionally provides a continuous burning pilot or provides an on-demand pilot, both such pilot operations having safety features for shutting down the main burner valve and relighting the pilot, in the event the pilot is extinguished.
Notwithstanding the benefits of the ""856 and ""963 patents, the system configuration of many gas burner heaters utilizing pilot control means and pilot ignition devices may have certain drawbacks. Often, the burner control system in the prior art devices includes a control system. The control system in prior art devices included a control board with an ignitor coil. The ignitor coil receives a low voltage input (approximately 150-200 volts) and develops a high voltage charge (approximately 15,000 to 25,000 volts). Typically, a terminal is connected to the output of the ignitor coil, and a high voltage wire is connected from the terminal to the ignitor rod. Because of hysteresis, the maximum distance allowable between the ignitor coil and the ignitor rod is approximately 10 ft. At distances greater than 10 feet between the ignitor coil and the ignitor rod, the high voltage and low impedance charge from the ignitor coil becomes unreliable. An unreliable charge may not provide a spark at the ignitor rod tip, thus resulting in unreliable relighting, and the potential formation of hydrocarbon condensation due to the temperature drop from the line heater being down. As a result, prior art control boards and ignitor coils were connected to ignitor rods with a high voltage wire at a span of less than approximately 10 ft.
Additionally, because the high voltage charge created by the ignitor coil, and the proximity of this charge to a lit gas supply, it is often necessary to place the control system and ignitor coil in an explosion proof container. By placing the control system and ignitor coil in a sealed chamber or cabinet, and often an explosion proof container, it is thought that in the event of a gas leak, a potential fire hazard through ignition of any leaked gas may be avoided. Such containers, however, are extremely expensive.
Accordingly, there is a need for a reliable and effective relighter system for a burner control system used with fuel pipeline heaters.
The present invention provides a system for providing a spark to a pilot burner for a heater for a fuel pipeline. The system generally includes a controller, a pilot burner and an ignition coil. The controller is located at a first location, and the pilot burner is located at a second location remote from the first location. Additionally, the ignition coil is also located at the second location. Typically, the ignition coil is electrically connected to the controller and it receives a voltage input from the controller. After receiving the voltage input, the ignition coil charges until it subsequently provides a voltage output. The ignition coil transfers a current based on the voltage output to create a spark in the pilot burner to ignite an air/fuel mixture in the pilot burner.
According to one aspect of the present invention, a low voltage line connects the controller and the ignition coil. In one embodiment, the first location is located a distance of approximately at least 10 feet from the second location. Additionally, the first location may be located a distance of approximately between 10 feet and 100 feet from the second location. Finally, the first location may be located a distance of at least 100 feet from the second location.
According to another aspect of the present invention, the voltage input the ignition coil receives from the controller is a low voltage input, and the voltage output of the ignition coil is a high voltage output. Generally, the low voltage input received from by the ignition coil is in the range of approximately 10 volts to approximately 200 volts.
According to another aspect of the present invention, an ignitor module is located at the second location and adjacent the pilot burner assembly. The ignitor module has a housing with the ignitor coil and a transformer therein. The transformer is electrically connected to the ignition coil. The transformer receives a first low voltage input from the controller and converts the first low voltage input to a second low voltage input. Typically, the second low voltage input is of a higher voltage than the first low voltage input. The second low voltage input is transferred from the transformer to the ignition coil. In one embodiment, the first low voltage input is approximately 12 volts, and the resulting second low voltage input is approximately 150-200 volts.
According to another aspect of the present invention, the ignitor coil and transformer are potted in the ignitor module housing in a thermoplastic resin. Additionally, the ignitor module also has a terminal strip electrically connected to the transformer and the ignitor coil, and a terminal extending from the ignitor coil and through a wall in the housing.
According to yet another aspect of the present invention, an ignitor rod is provided. The ignitor rod has a first end electrically connected to a terminal at an exit of the ignitor coil, and a second end adjacent the pilot burner. Current corresponding to the high voltage output is transferred from the ignitor coil to the ignitor rod. Conduction of the electrical current between the second end of the ignitor rod and the pilot burner causes a spark to ignite the air/fuel mixture in the pilot burner, thereby creating a pilot flame.
Other features and advantages of the invention will be apparent from the following specification taken in conjunction with the following drawings.